We moved into an old house, and one room still has the original 1890 horsehair lathed plaster all over. On the walls it's the consistency of sawdust held in place by a layer of paint. On the ceiling it is sagging and cracking, but I'd just as soon not fix it right now, which would trigger a bit more of a remodel than I want to do right now.
But my brain keeps thinking the sagging is getting worse...and worse...or maybe it isn't.
Is there a simple way to see if the sagging really is getting worse over time?